Regarding the lane keeping system,path tracking accuracy and lateral stability at high speeds need to be taken into account especially for commercial vehicles due to the characteristics of larger mass,longer wheelbase...Regarding the lane keeping system,path tracking accuracy and lateral stability at high speeds need to be taken into account especially for commercial vehicles due to the characteristics of larger mass,longer wheelbase and higher mass center.To improve the performance mentioned above comprehensively,the control strategy based on improved artificial potential field(APF)algorithm is proposed.In the paper,time to lane crossing(TLC)is introduced into the potential field function to enhance the accuracy of path tracking,meanwhile the vehicle dynamics parameters including yaw rate and lateral acceleration are chosen as the repulsive force field source.The lane keeping controller based on improved APF algorithm is designed and the stability of the control system is proved based on Lyapunov theory.In addition,adaptive inertial weight particle swarm optimization algorithm(AIWPSO)is applied to optimize the gain of each potential field function.The co-simulation results indicate that the comprehensive evaluation index respecting lane tracking accuracy and lateral stability is reduced remarkably.Finally,the proposed control strategy is verified by the HiL test.It provides a beneficial reference for dynamics control of commercial vehicles and enriches the theoretical development and practical application of artificial potential field method in the field of intelligent driving.展开更多
Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spec...Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.展开更多
Objective:To systematically evaluate the efficacy and safety of Duhuo Jisheng decoction combined with manipulation in the treatment of lumbar disc herniation.Method:We systematically searched 8 databases at home and a...Objective:To systematically evaluate the efficacy and safety of Duhuo Jisheng decoction combined with manipulation in the treatment of lumbar disc herniation.Method:We systematically searched 8 databases at home and abroad.Literature quality of the included studies was evaluated by the bias risk assessment tool of Cochrane collaboration network,and the Meta-analysis was performed by RevMan 5.3 software.Result:A total of 427 related literature were retrieved,and 12 studies were eventually included,involving 1153 patients.All studies were in Chinese.Meta-analysis results showed that the total effective rate of Duhuo Jisheng decoction combined with manipulation in the treatment of LDH was better than that of the control group(RR=1.23,95%CI[1.17,1.29],P<0.00001).Subgroup analysis showed that Duhuo Jisheng decoction combined with manipulation had a more significant effect than conventional treatment(RR=1.34,95%CI[1.20,1.50],P<0.00001),nonsteroidal anti-inflammatory drugs(RR=1.24,95%CI[1.12,1.37],P<0.0001),and Yaotongning capsules(RR=1.19,95%CI[1.10,1.29],P<0.0001).It has obvious advantages in improving VAS scores(MD=-1.19,95%CI-1.19[-1.87,-0.51],P=0.0006),but it has no obvious advantages in improving JOA scores(MD=2.6595%CI[0.06,5.24],P=0.05).In terms of safety,Duhuo Jisheng decoction combined with manipulation treatment reported fewer adverse events.Conclusion:The Duhuo Jisheng decoction combined with manipulation treatment can effectively relieve the clinical symptoms of patients with lumbar disc herniation,with obvious clinical efficacy,and fewer adverse events.But in view of the limitations of clinical studies,there are some limitations in this study,and more studies with high quality of evidence are needed to further confirm its efficacy and safety.展开更多
Nyquist Folding Receiver(NYFR)is a perceptron structure that realizes a low probability of intercept(LPI)signal analog to information.Aiming at the problem of LPI radar signal receiving,the time domain,frequency domai...Nyquist Folding Receiver(NYFR)is a perceptron structure that realizes a low probability of intercept(LPI)signal analog to information.Aiming at the problem of LPI radar signal receiving,the time domain,frequency domain,and time-frequency domain problems of signals intercepted by NYFR structure are studied.Combined with the time-frequency analysis(TFA)method,a radar recognition scheme based on deep learning(DL)is introduced,which can reliably classify common LPI radar signals.First,the structure of NYFR and its characteristics in the time domain,frequency domain,and time and frequency domain are analyzed.Then,the received signal is then converted into a time-frequency image(TFI).Finally,four kinds of DL algorithms are used to classify LPI radar signals.Simulation results demonstrate the correctness of the NYFR structure,and the effectiveness of the proposed recognition method is verified by comparison experiments.展开更多
Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering material...Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.展开更多
The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors wi...The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors with the coverage area of approximately 4 m^(2)in 5°-170°neutron diffraction angle.The neutron detection efficiency needs to be better than 40%at 1 A neutron wavelength.The spatial resolution should be better than 3 mm×50 mm in the horizontal and vertical directions respectively.We develop a one-dimensional scintillator neutron detector which is composed of the^(6)Li F/Zn S(Ag)scintillation screens,the wavelength-shifting fiber(WLSF)array,the silicon photomultipliers(Si PMs),and the self-designed application-specific integrated circuit(ASIC)readout electronics.The pixel size of the detector is designed as 3 mm×50 mm,and the neutron-sensitive area is 50 mm×200 mm.The performance of the detector prototype is measured using neutron beam 20#of the CSNS.The maximum counting rate of 247 k Hz,and the detection efficiency of63%at 1.59 A are obtained.The test results show that the performance of the detector fulfills the physical requirements of the ERNI under construction at the CSNS.展开更多
BACKGROUND Testicular mixed germ cell tumors(TMGCTs)are rare malignant tumors that are more common in men aged 20–40 years.TMGCTs comprise two or more types of germ cell tumors that primarily affect the testis.Their ...BACKGROUND Testicular mixed germ cell tumors(TMGCTs)are rare malignant tumors that are more common in men aged 20–40 years.TMGCTs comprise two or more types of germ cell tumors that primarily affect the testis.Their onset is undetectable;thus,early diagnosis is challenging.However,early recognition and diagnosis substantially improve patient prognosis.CASE SUMMARY We evaluated a rare case of TMGCT in a male patient presenting with recurrent fever and left supraclavicular lymphadenectasis instead of testicular enlargement and pain,which may easily lead to misdiagnosis.We report the clinical signs and symptoms,histopathological characteristics,and immunohistochemical results of this case of malignant TMGCT.CONCLUSION Our case,which was typical with multiple components,along with a literature review,may serve as a basis for early diagnosis.展开更多
The main function of electronic support measure system is to detect threating signals in order to take countermeasures against them. To accomplish this objective, a process of associating each interleaved pulse with i...The main function of electronic support measure system is to detect threating signals in order to take countermeasures against them. To accomplish this objective, a process of associating each interleaved pulse with its emitter must be done. This process is termed sorting or de-interleaving. A novel point symmetry based radar sorting(PSBRS) algorithm is addressed. In order to deal with all kinds of radar signals, the symmetry measure distance is used to cluster pulses instead of the conventional Euclidean distance. The reference points of the symmetrical clusters are initialized by the alternative fuzzy c-means(AFCM) algorithm to ameliorate the effects of noise and the false sorting. Besides,the density filtering(DF) algorithm is proposed to discard the noise pulses or clutter. The performance of the algorithm is evaluated under the effects of noise and missing pulses. It has been observed that the PSBRS algorithm can cope with a large number of noise pulses and it is completely independent of missing pulses.Finally, PSBRS is compared with some benchmark algorithms,and the simulation results reveal the feasibility and efficiency of the algorithm.展开更多
The Sallen–Key filter(S–K)is widely used in nuclear pulse signal processing because of its simple working principle and good performance.Related research has only reviewed the recursive numerical model of digital S...The Sallen–Key filter(S–K)is widely used in nuclear pulse signal processing because of its simple working principle and good performance.Related research has only reviewed the recursive numerical model of digital S–K using idealized parameters.The use of digital S–K thus has limitations under these circumstances.This paper comprehensively deduces a recursive numerical model of digital S–K and discusses the effects of resistance and capacitance on the filter quality factor,cutoff frequency and amplitude–frequency response.The numerical recursive function,transfer function and amplitude–frequency response are analyzed using different parameters.From a comparative analysis of the shaper in a simulation and an actual nuclear signal,an optimal parameter selection principle is obtained.Using different forming parameters,the energy resolution and pulse counting rate of the 55Fe energy spectrum are compared and analyzed based on a Si-PIN detector.Capacitance has a stronger influence on the Gaussian shape,whereas the influence of resistance is stronger on the shaping amplitude.展开更多
Nyquist folding receiver(NYFR) is a typical wideband analog-to-information architecture. Focusing on the noncooperative receiving, the pulse radar signal intercepted by the NYFR in time domain is analyzed. The NYFR ou...Nyquist folding receiver(NYFR) is a typical wideband analog-to-information architecture. Focusing on the noncooperative receiving, the pulse radar signal intercepted by the NYFR in time domain is analyzed. The NYFR outputs under different input conditions are investigated based on the extended Fourier transform(EFT) and the sampling theorem. Combining with the characteristic of the NYFR output in time domain, a new time of arrival(TOA) estimation method based on the energy envelope and the wavelet transform is proposed. The proposed estimation method can be adapted for the non-cooperative situation. It has no requirement for prior information to determine the threshold and is not necessary to transform the signal into baseband. Simulation results prove the correctness of the NYFR output expressions and show the efficacy of the proposed estimation method.展开更多
CR–RCm filters are widely used in nuclear energy spectrum measurement systems. The choice of parameters of a CR–RCm digital filter directly affects its performance in terms of energy resolution and pulse count rate ...CR–RCm filters are widely used in nuclear energy spectrum measurement systems. The choice of parameters of a CR–RCm digital filter directly affects its performance in terms of energy resolution and pulse count rate in digital nuclear spectrometer systems. A numerical recursive model of a CR differential circuit and RC integration circuit is derived, which shows that the shaping result of CR–RCm is determined by the adjustment parameter (k, it determines the shaping time of the shaper) and the integral number (m). Furthermore, the amplitude– frequency response of CR–RC^m is analyzed, which shows that it is a bandpass filter;the larger the shaping parameters (k and m), the narrower is the frequency band. CR–RC^m digital Gaussian shaping is performed on the actual sampled nuclear pulse signal under different shaping parameters. The energy spectrum of 137Cs is measured based on the LaBr3(Ce) detector under different parameters. The results show that the larger the shaping parameters (m and k), the closer the shaping result is to Gaussian shape, the wider is the shaped pulse, the higher is the energy resolution, and the lower is the pulse count rate. For the same batch of pulse signals, the energy resolution is increased from 3.8 to 3.5%, and the full energy peak area is reduced from 7815 to 6503. Thus, the optimal shaping parameters are m -3 and k -0.95. These research results can provide a design reference for the development of digital nuclear spectrometer measurement systems.展开更多
A novel identification method for point source,coherently distributed(CD) source and incoherently distributed(ICD) source is proposed.The differences among the point source,CD source and ICD source are studied.Accordi...A novel identification method for point source,coherently distributed(CD) source and incoherently distributed(ICD) source is proposed.The differences among the point source,CD source and ICD source are studied.According to the different characters of covariance matrix and general steering vector of the array received source,a second order blind identification method is used to separate the sources,the mixing matrix could be obtained.From the mixing matrix,the type of the source is identified by using an amplitude criterion.And the direction of arrival for the array received source is estimated by using the matching pursuit algorithm from the vectors of the mixing matrix.Computer simulations validate the efficiency of the method.展开更多
Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O_2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of...Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O_2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of 0.1 m A/cm2, and the capacity is about 2.3 times as that of the pristine KB. When the batteries are cycled with different restricted capacity, the boron-doped Ketjenblack based cathodes exhibits higher discharge platform and longer cycle life than Ketjenblack based cathodes. Additionally, the boron-doped Ketjenblack also shows a superior electrocatalytic activity for oxygen reduction in 0.1 mol/L KOH aqueous solution. The improvement in catalytic activity results from the defects and activation sites introduced by boron doping.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51605199,U20A20333,52225212)Six Talent Peak Funding Projects in Jiangsu Province of China(Grant No.2019-GDZB-084)Key Science and Technology Support Program in Taizhou City of China(Grant No.TG202307).
文摘Regarding the lane keeping system,path tracking accuracy and lateral stability at high speeds need to be taken into account especially for commercial vehicles due to the characteristics of larger mass,longer wheelbase and higher mass center.To improve the performance mentioned above comprehensively,the control strategy based on improved artificial potential field(APF)algorithm is proposed.In the paper,time to lane crossing(TLC)is introduced into the potential field function to enhance the accuracy of path tracking,meanwhile the vehicle dynamics parameters including yaw rate and lateral acceleration are chosen as the repulsive force field source.The lane keeping controller based on improved APF algorithm is designed and the stability of the control system is proved based on Lyapunov theory.In addition,adaptive inertial weight particle swarm optimization algorithm(AIWPSO)is applied to optimize the gain of each potential field function.The co-simulation results indicate that the comprehensive evaluation index respecting lane tracking accuracy and lateral stability is reduced remarkably.Finally,the proposed control strategy is verified by the HiL test.It provides a beneficial reference for dynamics control of commercial vehicles and enriches the theoretical development and practical application of artificial potential field method in the field of intelligent driving.
基金supported by the Key Projects of the 2022 National Defense Science and Technology Foundation Strengthening Plan 173 (Grant No.2022-173ZD-010)the Equipment PreResearch Foundation of The State Key Laboratory (Grant No.6142101200204)。
文摘Wideband spectrum sensing with a high-speed analog-digital converter(ADC) presents a challenge for practical systems.The Nyquist folding receiver(NYFR) is a promising scheme for achieving cost-effective real-time spectrum sensing,which is subject to the complexity of processing the modulated outputs.In this case,a multipath NYFR architecture with a step-sampling rate for the different paths is proposed.The different numbers of digital channels for each path are designed based on the Chinese remainder theorem(CRT).Then,the detectable frequency range is divided into multiple frequency grids,and the Nyquist zone(NZ) of the input can be obtained by sensing these grids.Thus,high-precision parameter estimation is performed by utilizing the NYFR characteristics.Compared with the existing methods,the scheme proposed in this paper overcomes the challenge of NZ estimation,information damage,many computations,low accuracy,and high false alarm probability.Comparative simulation experiments verify the effectiveness of the proposed architecture in this paper.
基金Key projects of the national natural science foundation of China(No.81930118)National support program for leading talents in traditional Chinese medicine--"Qi-huang scholars"program+1 种基金Key research projects of the 13th five-year plan of the China academy of Chinese medical sciences(No.ZZ10-022)Jiangxi province postdoctoral subsidy project(No.2018RC13).
文摘Objective:To systematically evaluate the efficacy and safety of Duhuo Jisheng decoction combined with manipulation in the treatment of lumbar disc herniation.Method:We systematically searched 8 databases at home and abroad.Literature quality of the included studies was evaluated by the bias risk assessment tool of Cochrane collaboration network,and the Meta-analysis was performed by RevMan 5.3 software.Result:A total of 427 related literature were retrieved,and 12 studies were eventually included,involving 1153 patients.All studies were in Chinese.Meta-analysis results showed that the total effective rate of Duhuo Jisheng decoction combined with manipulation in the treatment of LDH was better than that of the control group(RR=1.23,95%CI[1.17,1.29],P<0.00001).Subgroup analysis showed that Duhuo Jisheng decoction combined with manipulation had a more significant effect than conventional treatment(RR=1.34,95%CI[1.20,1.50],P<0.00001),nonsteroidal anti-inflammatory drugs(RR=1.24,95%CI[1.12,1.37],P<0.0001),and Yaotongning capsules(RR=1.19,95%CI[1.10,1.29],P<0.0001).It has obvious advantages in improving VAS scores(MD=-1.19,95%CI-1.19[-1.87,-0.51],P=0.0006),but it has no obvious advantages in improving JOA scores(MD=2.6595%CI[0.06,5.24],P=0.05).In terms of safety,Duhuo Jisheng decoction combined with manipulation treatment reported fewer adverse events.Conclusion:The Duhuo Jisheng decoction combined with manipulation treatment can effectively relieve the clinical symptoms of patients with lumbar disc herniation,with obvious clinical efficacy,and fewer adverse events.But in view of the limitations of clinical studies,there are some limitations in this study,and more studies with high quality of evidence are needed to further confirm its efficacy and safety.
基金the National Natural Science Foundation of China(Nos.51801156 and 52074231)the Chongqing Natural Science Foundation,China(No.cstc2020jcyj-msxm X1056)for the financial support to this work。
基金supported by the National Defence Pre-research Foundation of China。
文摘Nyquist Folding Receiver(NYFR)is a perceptron structure that realizes a low probability of intercept(LPI)signal analog to information.Aiming at the problem of LPI radar signal receiving,the time domain,frequency domain,and time-frequency domain problems of signals intercepted by NYFR structure are studied.Combined with the time-frequency analysis(TFA)method,a radar recognition scheme based on deep learning(DL)is introduced,which can reliably classify common LPI radar signals.First,the structure of NYFR and its characteristics in the time domain,frequency domain,and time and frequency domain are analyzed.Then,the received signal is then converted into a time-frequency image(TFI).Finally,four kinds of DL algorithms are used to classify LPI radar signals.Simulation results demonstrate the correctness of the NYFR structure,and the effectiveness of the proposed recognition method is verified by comparison experiments.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11975255 and 11875273)Guangdong Basic and Applied Basic Research Foundation (Grant No. 2020B1515120025)。
文摘Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.
基金the National Natural Science Foundation of China(Grant Nos.11875273,U1832111,61964001,and 12275049)the Science Foundation of Guangdong Province of China(Grant No.2020B1515120025)+3 种基金the Neutron Physics Laboratory Funding of China Academy of Engineering Physics(Grant No.2018BC03)the General Project of Jiangxi Province Key Research and Development Program(Grant No.20212BBG73012)the Key Scientific Research Projects of Henan Higher Education Institutions(Grant Nos.23A490002 and 24A490001)the Engineering Research Center of Nuclear Technology Application(Grant No.HJSJYB2021-4)。
文摘The energy-resolved neutron imaging spectrometer(ERNI)will be installed in 2022 according to the spectrometer construction plan of the China Spallation Neutron Source(CSNS).The instrument requires neutron detectors with the coverage area of approximately 4 m^(2)in 5°-170°neutron diffraction angle.The neutron detection efficiency needs to be better than 40%at 1 A neutron wavelength.The spatial resolution should be better than 3 mm×50 mm in the horizontal and vertical directions respectively.We develop a one-dimensional scintillator neutron detector which is composed of the^(6)Li F/Zn S(Ag)scintillation screens,the wavelength-shifting fiber(WLSF)array,the silicon photomultipliers(Si PMs),and the self-designed application-specific integrated circuit(ASIC)readout electronics.The pixel size of the detector is designed as 3 mm×50 mm,and the neutron-sensitive area is 50 mm×200 mm.The performance of the detector prototype is measured using neutron beam 20#of the CSNS.The maximum counting rate of 247 k Hz,and the detection efficiency of63%at 1.59 A are obtained.The test results show that the performance of the detector fulfills the physical requirements of the ERNI under construction at the CSNS.
文摘BACKGROUND Testicular mixed germ cell tumors(TMGCTs)are rare malignant tumors that are more common in men aged 20–40 years.TMGCTs comprise two or more types of germ cell tumors that primarily affect the testis.Their onset is undetectable;thus,early diagnosis is challenging.However,early recognition and diagnosis substantially improve patient prognosis.CASE SUMMARY We evaluated a rare case of TMGCT in a male patient presenting with recurrent fever and left supraclavicular lymphadenectasis instead of testicular enlargement and pain,which may easily lead to misdiagnosis.We report the clinical signs and symptoms,histopathological characteristics,and immunohistochemical results of this case of malignant TMGCT.CONCLUSION Our case,which was typical with multiple components,along with a literature review,may serve as a basis for early diagnosis.
基金supported by the National Natural Science Foundation of China(61172116)
文摘The main function of electronic support measure system is to detect threating signals in order to take countermeasures against them. To accomplish this objective, a process of associating each interleaved pulse with its emitter must be done. This process is termed sorting or de-interleaving. A novel point symmetry based radar sorting(PSBRS) algorithm is addressed. In order to deal with all kinds of radar signals, the symmetry measure distance is used to cluster pulses instead of the conventional Euclidean distance. The reference points of the symmetrical clusters are initialized by the alternative fuzzy c-means(AFCM) algorithm to ameliorate the effects of noise and the false sorting. Besides,the density filtering(DF) algorithm is proposed to discard the noise pulses or clutter. The performance of the algorithm is evaluated under the effects of noise and missing pulses. It has been observed that the PSBRS algorithm can cope with a large number of noise pulses and it is completely independent of missing pulses.Finally, PSBRS is compared with some benchmark algorithms,and the simulation results reveal the feasibility and efficiency of the algorithm.
基金supported by the National Natural Science Foundation of China(Nos.11665001 and 41864007)China Scholarship Council(No.201708360170)One Hundred People Sail in Jiangxi Province,Foundation of Key Laboratory for Radioactive Geology and Exploration Technology(No.RGET1309)
文摘The Sallen–Key filter(S–K)is widely used in nuclear pulse signal processing because of its simple working principle and good performance.Related research has only reviewed the recursive numerical model of digital S–K using idealized parameters.The use of digital S–K thus has limitations under these circumstances.This paper comprehensively deduces a recursive numerical model of digital S–K and discusses the effects of resistance and capacitance on the filter quality factor,cutoff frequency and amplitude–frequency response.The numerical recursive function,transfer function and amplitude–frequency response are analyzed using different parameters.From a comparative analysis of the shaper in a simulation and an actual nuclear signal,an optimal parameter selection principle is obtained.Using different forming parameters,the energy resolution and pulse counting rate of the 55Fe energy spectrum are compared and analyzed based on a Si-PIN detector.Capacitance has a stronger influence on the Gaussian shape,whereas the influence of resistance is stronger on the shaping amplitude.
基金supported by the National Natural Science Foundation of China(61571088)the State High-Tech Development Plan(the 863 Program)(2015AA7031093B2015AA8098088B)
文摘Nyquist folding receiver(NYFR) is a typical wideband analog-to-information architecture. Focusing on the noncooperative receiving, the pulse radar signal intercepted by the NYFR in time domain is analyzed. The NYFR outputs under different input conditions are investigated based on the extended Fourier transform(EFT) and the sampling theorem. Combining with the characteristic of the NYFR output in time domain, a new time of arrival(TOA) estimation method based on the energy envelope and the wavelet transform is proposed. The proposed estimation method can be adapted for the non-cooperative situation. It has no requirement for prior information to determine the threshold and is not necessary to transform the signal into baseband. Simulation results prove the correctness of the NYFR output expressions and show the efficacy of the proposed estimation method.
基金supported by National Natural Science Foundation of China(Nos.11665001,41864007)National Key R&D Project(No.2017YFF0106503)+1 种基金China Scholarship Council(No.201708360170)One Hundred People Sail in Jiangxi Province,Open-ended Foundation from the Chinese Engineering Research Center(No.HJSJYB2014-03)
文摘CR–RCm filters are widely used in nuclear energy spectrum measurement systems. The choice of parameters of a CR–RCm digital filter directly affects its performance in terms of energy resolution and pulse count rate in digital nuclear spectrometer systems. A numerical recursive model of a CR differential circuit and RC integration circuit is derived, which shows that the shaping result of CR–RCm is determined by the adjustment parameter (k, it determines the shaping time of the shaper) and the integral number (m). Furthermore, the amplitude– frequency response of CR–RC^m is analyzed, which shows that it is a bandpass filter;the larger the shaping parameters (k and m), the narrower is the frequency band. CR–RC^m digital Gaussian shaping is performed on the actual sampled nuclear pulse signal under different shaping parameters. The energy spectrum of 137Cs is measured based on the LaBr3(Ce) detector under different parameters. The results show that the larger the shaping parameters (m and k), the closer the shaping result is to Gaussian shape, the wider is the shaped pulse, the higher is the energy resolution, and the lower is the pulse count rate. For the same batch of pulse signals, the energy resolution is increased from 3.8 to 3.5%, and the full energy peak area is reduced from 7815 to 6503. Thus, the optimal shaping parameters are m -3 and k -0.95. These research results can provide a design reference for the development of digital nuclear spectrometer measurement systems.
文摘A novel identification method for point source,coherently distributed(CD) source and incoherently distributed(ICD) source is proposed.The differences among the point source,CD source and ICD source are studied.According to the different characters of covariance matrix and general steering vector of the array received source,a second order blind identification method is used to separate the sources,the mixing matrix could be obtained.From the mixing matrix,the type of the source is identified by using an amplitude criterion.And the direction of arrival for the array received source is estimated by using the matching pursuit algorithm from the vectors of the mixing matrix.Computer simulations validate the efficiency of the method.
基金supported by the MOST(Grant nos.2013CB934000and 2014DFG71590)Beijing Municipal Program(Grant no.YETP0157)
文摘Boron-doped Ketjenblack is attempted as cathode catalyst for non-aqueous rechargeable Li–O_2 batteries. The boron-doped Ketjenblack delivers an extremely high discharge capacity of 7193 m Ah/g at a current density of 0.1 m A/cm2, and the capacity is about 2.3 times as that of the pristine KB. When the batteries are cycled with different restricted capacity, the boron-doped Ketjenblack based cathodes exhibits higher discharge platform and longer cycle life than Ketjenblack based cathodes. Additionally, the boron-doped Ketjenblack also shows a superior electrocatalytic activity for oxygen reduction in 0.1 mol/L KOH aqueous solution. The improvement in catalytic activity results from the defects and activation sites introduced by boron doping.
